This invention relates to a mount apparatus for coupling a rotatable apparatus to the shaft of a rotating drive unit such as a dynamoelectric machine and particularly to the mounting of a tachometer or other related driven device to a rotary motor.
Motors and other dynamoelectric machines are constructed using an annular stator unit within a round main frame closed by end frames and a rotor rotatably mounted within the motor end frames. The rotor includes a rotor shaft which is supported in bearing in the motor end frames. In various motors, speed detecting devices or other control devices are mounted to the motor end frame and include a rotating member which is coupled to the motor shaft. Speed detecting devices may, for example, include a tachometer, an optical encoder or other similar device for detecting the speed of the rotor. Other devices which are often mounted to the motor and supported by the motor frame include brake devices, clutch devices, external fans and the like. Generally, the devices of interest herein have an outer member mounted in fixed relationship to the motor frame and a rotating member coupled to the motor shaft.
In various applications, accurate mounting of the auxiliary rotatable component or device is required to produce optimum operation and more particularly to prevent damage to the device and the coupling thereof during motor operation.
A particular application to which the present invention has been applied is the mounting of a tachometer to the end face or end frame member of an electric motor, and particularly totally enclosed, fan-cooled motors. In prior art systems, the end frame includes an annular mounting unit encircling the shaft structure with a mounting plate fixedly secured to the unit to support the tachometer with a rotating input member coupled to the motor shaft. In the mounting of tachometer and other motor-mounted and driven devices, the inventor has realized that the tachometer mount must have a total run-out within close specifications to insure proper operation and long life for the tachometer and coupling. Thus, the mounting unit should be accurately set for both radial run-out and axial run-out of the apparatus with respect to the motor frame to which the mounting unit is secured. Further, the mounting unit should provide a long life support generally corresponding to the anticipated motor life, and preferably permit a rapid and accurate attachment of the apparatus, and thereby provide a cost-effective mounting.